If the nature of the conditions change dont you call it Vmc then, and not Vmca anymore ? What does Vmc mean then ?
From a pilot's point of view (i.e. oversimplisitc!!), I've only ever understood the following:
VMCG to be the minumum control speed
ON THE GROUND
VMCA to be the miminum control speed
'airbourne', although I agree this term is a little vague.
VMCL to be the minimum control speed in the landing configuration, which, although technically still airbourne, is likely to be a different (lesser) speed than VMCA, with high lift and drag devices out and a significantly augmented wing shape.
As demonstrated by the last post, things can all get very detailed very quickly on this subject
